The United States has adopted a digital television standard for the transmission of digital television signals. This standard specifies that data is to be transmitted in the form of packets to digital television receivers. For example, video data are transmitted in video packets, audio data are transmitted in audio packets, and certain data including, inter alia, the physical, virtual, and NTSC channels of the corresponding digital television signal are transmitted in packets containing program system information protocol data tables (PSIP data tables). There are several types of PSIP tables, each containing specific information as set forth in ATSC document A/65. The table relevant to this invention is referred to as the virtual channel table (VCT) which normally occupies between one and three packets.
The physical channel corresponds to the carrier frequency that is being used to transmit the digital television signal. The virtual channel is typically, although not necessarily, the channel number over which the corresponding analog television signal is received in the receiving area covered by the digital television signal. For example, the source of a particular digital television signal may be associated with analog channel number 7 in that source's coverage area but may actually be transmitting on a carrier corresponding to channel 30. In this example, channel 7 is the virtual channel and channel 30 is the physical channel. The virtual channel number is frequently displayed by a television such as when a channel change is effected. The NTSC channel is identified by an analog NTSC carrier and is the analog channel assigned to the corresponding source of the digital television signal.
Digital television signals are typically transmitted over the air, over cable, by way of satellites, etc. In some cases, certain impairments may be present which make good reception at particular receiving locations difficult. For example, a hill may interfere with or block the broadcast of a digital television signal from a transmitter to a receiver so that the digital television signal cannot be adequately received by the receiver.
The present invention is directed to a digital television translator which receives the digital television signal, appropriately processes the digital television signal, and forwards the processed digital television signal on so that the digital television signal may be adequately received by a receiver. For example, the translator may be positioned at the impairment, such as on top of the aforementioned hill, so that the harmful effects of the impairment are avoided.